... kind of grains, we specially process the ingots, separate the magnetic material, and sieve the grains carefully to get a complete range of ... kinds of vitrified bonded grinding wheels, resign bonded grinding wheels and cut-off wheels.The tough, strong aluminum oxide characteristic also ... Gravity 3.92Hardness 2090 Knoop scale, 9.0 Mohs scaleMagnetic Material 0.0076% Grain Sizes Available (F):12, 14, 16, ...